Clear softening compositions are known in the art. For example, EP-A-0,404,471 discloses clear softening compositions with at least 20% by weight softener and at least 5% by weight of a short chain organic acid.
Formulating softening compositions which are clear is however not the only condition required of softening compositions. Indeed, such compositions are expected to provide an effective softening performance on the treated fabric. In this respect, EP-A-0,550,361 discloses softening compounds with specific molar ratios of fatty acid fraction to tertiary amine which provide effective softening performance without being detrimental to the fluidity and stability of composition containing said compound.
It is now an object to provide a softening compound which provides effective softening performance.
Still another object of the invention, is to provide a composition containing said compound which are clear but still not detrimental to the fluidity and stability of composition.
These objects have now surprisingly been met by producing the softening compound from the condensation of fatty acids with triethanolamine, wherein the condensation occurs for a period such that the condensation product has an acid value (AV) of less than 6.5, the condensation product subsequently being quaternized.
The AV of the compound is measured on the condensation product before the quaternisation step by the test method defined hereinafter.
For optimum softness benefit, it is preferred that the reactants are present in a molar ratio of fatty acid fraction to triethanolamine of from 1:1 to 2.5:1.
The finding that a lower acid value of the invention compound leads to higher softness performance when using the invention compound is very surprising and unexpected. Indeed, as known from GB 2,039,556, the addition of fatty acid provide an increase in the softness performance of the softening composition. The Applicant, in this respect, has found that the addition of fatty acid, instead of decreasing the acid value, increased the acid value. Accordingly, it was generally believed that the softness performance in relation to the acid value followed a curve showing a maximum at an AV above 10. To the contrary, it has been found that the softness performance followed a line whereby the higher the acid value, the less softening performance is obtained.
By effective softening performance, it is meant that the compound of the present invention provides better softening performance to fabrics compared to fabrics which have been treated with a similar compound but with an AV above 6.5. In a preferred embodiment, the compound of the invention provides better softness performance on treated fabrics therewith compared to compounds having the hereinbelow described molar ratios but not the specified AV.